From e50b1e016723abb43ad0aef5abe84a2cd6621d5a Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Lo=C3=AFc=20Gr=C3=A9goire?= <loic@gregoire.dev>
Date: Thu, 18 Jun 2026 18:54:38 -0400
Subject: [PATCH] ps: initial process subsystem

---
 src/ex/fireworks.zig    | 35 ++++++---------------------------
 src/ex/init.zig         | 43 ++++++-----------------------------------
 src/kern/init.zig       |  3 ++-
 src/kern/thread.zig     |  7 ++++---
 src/platform/pc/smp.zig |  4 +---
 src/proc/private.zig    | 28 +++++++++++++++++++++++++++
 src/proc/root.zig       | 16 +++++++++++++++
 src/proc/thread.zig     | 28 +++++++++++++++++++++++++++
 src/root.zig            |  1 +
 9 files changed, 92 insertions(+), 73 deletions(-)
 create mode 100644 src/proc/private.zig
 create mode 100644 src/proc/root.zig
 create mode 100644 src/proc/thread.zig

diff --git a/src/ex/fireworks.zig b/src/ex/fireworks.zig
index 7287dbe..63f8648 100644
--- a/src/ex/fireworks.zig
+++ b/src/ex/fireworks.zig
@@ -3,6 +3,7 @@ const std = @import("std");
 const r = @import("root");
 const ke = r.ke;
 const mm = r.mm;
+const ps = r.ps;
 const sintab = @import("sintab.zig");
 
 var pixel_buffer: [*]u8 = undefined;
@@ -30,20 +31,8 @@ fn plot_pixel(x: i64, y: i64, color: u32) void {
     @as(*u32, @ptrCast(@alignCast(&pixel_buffer[pixel_offset]))).* = color;
 }
 
-fn read_tsc() u64 {
-    var lo: u32 = 0;
-    var hi: u32 = 0;
-
-    asm volatile ("rdtsc"
-        : [lo] "={eax}" (lo),
-          [hi] "={edx}" (hi),
-    );
-
-    return (@as(u64, hi) << 32) | @as(u64, lo);
-}
-
 fn rand_tsc_based() u32 {
-    const tsc = read_tsc();
+    const tsc = ke.time.read_time();
     const lo: u32 = @truncate(tsc);
     const hi: u32 = @truncate(tsc >> 32);
     return lo ^ hi;
@@ -163,26 +152,14 @@ fn particle(param: ?*anyopaque) void {
     ke.sched.block();
 }
 
-fn make_thread(entry: *const fn (?*anyopaque) void, arg: ?*anyopaque) *ke.Thread {
-    var ret: *ke.Thread = mm.zone.gpa.create(ke.Thread) catch @panic("oom");
-    const stack = mm.heap.alloc(r.kib(16)) catch @panic("wtf");
-
-    ret.init(@intFromPtr(stack), r.kib(16), entry, arg);
-
-    ret.priority = ke.Thread.Priority.default;
-    ret.base_priority = ke.Thread.Priority.default;
-
-    return ret;
-}
-
 fn spawn_particle(arg: ?*anyopaque) void {
-    const thread = make_thread(&particle, arg);
-    ke.sched.enqueue(thread);
+    const t = ps.thread.create_kernel(ke.Thread.Priority.default, &particle, arg) catch @panic("OOM");
+    ke.sched.enqueue(&t.kern);
 }
 
 fn spawn_explodeable() void {
-    const thread = make_thread(&explodeable, null);
-    ke.sched.enqueue(thread);
+    const t = ps.thread.create_kernel(ke.Thread.Priority.default, &explodeable, null) catch @panic("OOM");
+    ke.sched.enqueue(&t.kern);
 }
 
 fn explodeable(_: ?*anyopaque) void {
diff --git a/src/ex/init.zig b/src/ex/init.zig
index d56f591..b6e0e4a 100644
--- a/src/ex/init.zig
+++ b/src/ex/init.zig
@@ -4,11 +4,10 @@ const pl = r.pl;
 const ke = r.ke;
 const mm = r.mm;
 const ex = r.ex;
+const ps = r.ps;
 const amd64 = @import("arch");
 const turnstile = ke.private.turnstile;
 
-var thread0: ke.Thread = undefined;
-
 var mtx: ke.private.mutex.Mutex = .init();
 var shared_counter: usize = 0;
 
@@ -20,48 +19,18 @@ fn mutex_test(_: ?*anyopaque) void {
     }
 }
 
-fn make_thread(entry: *const fn (?*anyopaque) void, arg: ?*anyopaque) *ke.Thread {
-    var ret: *ke.Thread = mm.zone.gpa.create(ke.Thread) catch @panic("oom");
-    const stack = mm.heap.alloc(r.kib(64)) catch @panic("wtf");
-
-    std.log.info("Stack = {*}", .{stack});
-
-    ret.init(@intFromPtr(stack), r.kib(64), entry, arg);
-
-    ret.priority = ke.Thread.Priority.default;
-    ret.base_priority = ret.priority;
-    ret.turnstile = mm.zone.gpa.create(ke.private.turnstile.Turnstile) catch @panic("oom");
-    ret.turnstile.* = .{
-        .link = undefined,
-        .next_free = null,
-        .obj = undefined,
-        .owner = null,
-        .boost_link = undefined,
-        .donated = null,
-        .queues = undefined,
-        .waiters = 0,
-    };
-
-    ret.turnstile.queues[0].init();
-    ret.turnstile.queues[1].init();
-    ret.turnstile_waiter = null;
-
-    return ret;
-}
-
 pub fn init(boot_info: *pl.BootInfo) void {
     mm.init(boot_info);
 
     pl.late_init(boot_info);
     mm.late_init();
     ke.sched.late_init();
-    ke.private.turnstile.init_turnstiles();
+    ps.init();
 
     if (false) {
         if (boot_info.framebuffer != null) {
-            const sp = mm.heap.alloc(r.kib(16)) catch @panic("oom");
-            thread0.init(@intFromPtr(sp), r.kib(16), ex.fireworks.start, boot_info);
-            ke.sched.enqueue(&thread0);
+            const t = ps.thread.create_kernel(ke.Thread.Priority.default, ex.fireworks.start, boot_info) catch @panic("oom");
+            ke.sched.enqueue(&t.kern);
         }
 
         while (true) {}
@@ -70,8 +39,8 @@ pub fn init(boot_info: *pl.BootInfo) void {
     const ipl = ke.ipl.raise(.Dispatch);
 
     for (0..10) |_| {
-        const t = make_thread(mutex_test, null);
-        ke.sched.enqueue(t);
+        const t = ps.thread.create_kernel(ke.Thread.Priority.default, mutex_test, null) catch @panic("oom");
+        ke.sched.enqueue(&t.kern);
     }
 
     ke.ipl.lower(ipl);
diff --git a/src/kern/init.zig b/src/kern/init.zig
index 94009a4..18776ad 100644
--- a/src/kern/init.zig
+++ b/src/kern/init.zig
@@ -14,8 +14,9 @@ pub fn init(boot_info: *pl.BootInfo) linksection(r.init) void {
     std.log.info("Welcome to the machine", .{});
     pl.early_init(boot_info);
     ki.cpu.init_cpu(0);
+    ki.turnstile.init_turnstiles();
 
-    thread0.init(@intFromPtr(&stack), r.kib(16), ki.sched.idle, null);
+    thread0.init(@intFromPtr(&stack), r.kib(16), ke.Thread.Priority.idle, ki.sched.idle, null);
     thread0.priority = 0;
     thread0.base_priority = 0;
     thread0.pinned = true;
diff --git a/src/kern/thread.zig b/src/kern/thread.zig
index 063686d..8c6f97a 100644
--- a/src/kern/thread.zig
+++ b/src/kern/thread.zig
@@ -111,15 +111,16 @@ pub const Thread = struct {
     /// Initialize a thread.
     /// - `stack`: Address of the **base** of the stack on which the initial context for the thread is built
     /// - `stack_size`: Size of the stack
+    /// - `prio`: Base priority of the thread
     /// - `entry`: Entry point of the thread
     /// - `arg`: Extraneous argument to be passed to `entry`
-    pub fn init(thread: *Thread, stack: r.VAddr, stack_size: usize, entry: *const fn (?*anyopaque) void, arg: ?*anyopaque) void {
+    pub fn init(thread: *Thread, stack: r.VAddr, stack_size: usize, prio: u8, entry: *const fn (?*anyopaque) void, arg: ?*anyopaque) void {
         thread.* = .{
             .context = .init(stack, stack_size, entry, arg),
             .lock = .init(),
             .nice = 0,
-            .priority = Thread.Priority.default,
-            .base_priority = Thread.Priority.default,
+            .priority = prio,
+            .base_priority = prio,
             .inherited_prio = 0,
             .sleep_start = 0,
             .sleep_time = 0,
diff --git a/src/platform/pc/smp.zig b/src/platform/pc/smp.zig
index 0708dc0..ab2a70c 100644
--- a/src/platform/pc/smp.zig
+++ b/src/platform/pc/smp.zig
@@ -40,10 +40,8 @@ fn ap_entry(cpu_id: u32) callconv(.c) noreturn {
 fn make_thread(entrypoint: *const fn (?*anyopaque) void, stack: usize) *ke.Thread {
     const td = mm.zone.gpa.create(ke.Thread) catch @panic("Failed to allocate thread for AP");
 
-    td.init(stack, r.kib(32), entrypoint, null);
+    td.init(stack, r.kib(32), ke.Thread.Priority.idle, entrypoint, null);
 
-    td.priority = 0;
-    td.base_priority = 0;
     td.pinned = true;
     return td;
 }
diff --git a/src/proc/private.zig b/src/proc/private.zig
new file mode 100644
index 0000000..eb90a19
--- /dev/null
+++ b/src/proc/private.zig
@@ -0,0 +1,28 @@
+const r = @import("root");
+const ke = r.ke;
+const ki = ke.private;
+const mm = r.mm;
+
+pub const thread = @import("thread.zig");
+
+pub var turnstile_zone: mm.zone.TypedZone(ki.turnstile.Turnstile) = undefined;
+
+fn turnstile_ctor(ts: *ki.turnstile.Turnstile) void {
+    ts.* = .{
+        .link = undefined,
+        .next_free = null,
+        .obj = undefined,
+        .owner = null,
+        .boost_link = undefined,
+        .donated = null,
+        .queues = undefined,
+        .waiters = 0,
+    };
+    ts.queues[0].init();
+    ts.queues[1].init();
+}
+
+/// Initialize the process subsystem.
+pub fn init() void {
+    turnstile_zone.init("turnstiles", .{ .ctor = turnstile_ctor });
+}
diff --git a/src/proc/root.zig b/src/proc/root.zig
new file mode 100644
index 0000000..2bfa1b2
--- /dev/null
+++ b/src/proc/root.zig
@@ -0,0 +1,16 @@
+//! Higher-level process management.
+
+// === Exported modules ===
+pub const private = @import("private.zig");
+
+const p = private;
+
+// === Exported types ===
+pub const Thread = p.thread.Thread;
+
+// === Exported interfaces ===
+pub const thread = struct {
+    pub const create_kernel = p.thread.create_kernel;
+};
+
+pub const init = p.init;
diff --git a/src/proc/thread.zig b/src/proc/thread.zig
new file mode 100644
index 0000000..ab29970
--- /dev/null
+++ b/src/proc/thread.zig
@@ -0,0 +1,28 @@
+//! Higher-level thread management.
+const r = @import("root");
+const psp = r.ps.private;
+const ke = r.ke;
+const ki = ke.private;
+const mm = r.mm;
+
+const kernel_thread_stack_size = r.kib(16);
+
+/// Higher-level wrapper over a thread.
+pub const Thread = struct {
+    /// Lower-level part of the thread.
+    kern: ke.Thread,
+};
+
+/// Create a kernel thread.
+/// - `prio`: base priority of the thread.
+/// - `entry`: entry point.
+/// - `arg`: argument passed to `entry`.
+pub fn create_kernel(prio: u8, entry: *const fn (arg: ?*anyopaque) void, arg: ?*anyopaque) !*Thread {
+    var td = try mm.zone.gpa.create(Thread);
+    const stack = try mm.heap.alloc(kernel_thread_stack_size);
+
+    td.kern.init(@intFromPtr(stack), kernel_thread_stack_size, prio, entry, arg);
+    td.kern.turnstile = try psp.turnstile_zone.create();
+
+    return td;
+}
diff --git a/src/root.zig b/src/root.zig
index c783ecf..56a2b55 100644
--- a/src/root.zig
+++ b/src/root.zig
@@ -6,6 +6,7 @@ pub const rtl = @import("rtl");
 pub const ksyms = @import("ksyms");
 pub const arch = @import("arch");
 pub const mm = @import("mm/root.zig");
+pub const ps = @import("proc/root.zig");
 
 const config = @import("config");